分析应用题的思考方法(7)——增元法

有些特殊应用题数据很少,在分析解答时,我们可以把一些未知的数量用字母表示,直接参与列式或运算,但有些字母并不需要求出确定的值,它们起的只是“桥梁”的作用。这种解题思路和方法就是增元法。

增元法在解方程中的应用

对于一些看起来较复杂的整式方程、分式方程和无理方程,我们可应用增元法（即增设一个未知数）将原方程转化为方程组,实现问题的顺利求解,现举例说明如下,供初中师生参考.

增元法在解方程中的应用

对于一些看起来较复杂的整式方程、分式方程和无理方程，在解方程时，我们总想尽力消元以减少元的个数求解，但在解某些方程时，情况恰好相反，巧妙地增设元，使方程由一元变多元，方程反倒容易求解，不妨称这种方法为增元法．本文旨在说明用增元法解某些特殊的方程．现分类举例说明如下，供参考．

增元法在求解三次根式方程中的运用

三次根式方程虽然不是初中数学的重点内容,但在各地各类考试或数学竞赛试题中时有出现.本文利用增元法巧解有关三次根式方程,供大家参考。

例谈用增元法和主元法求解代数题

在解代数问题中，消元法与换元法是两种极其常用的方法．这里介绍另外两种在化简求值时十分有用的方法：增元法与主元法．请看下面几则实例．

增元法在解方程中的应用

对于一些看起来较复杂的整式方程、分式方程和无理方程，我们可应用增元法（即：增设一个未知数）将原方程转化为方程组，实现问题的顺利求解，现举例说明如下．

Construction of retroviral vector carrying HSV tk gene under control of human AFP enhancer core sequence and human pgk promotor *

AIM Tenstruct retroviral vector bringing HSV tk gene under control by human AFP enhancer core sequence and human pgk promotor.

Vibration analysis of wind tunnel support

In order to enable a wind tunnel support to have a high enough natural frequency to prevent experiencing mechanical resonance and excessive vibration displacement, five kinds of wind tunnel support structures have been simulated and analyzed individually under five different load conditions by means of a nonlinear finite element numerical method. With natural frequency and three directions vibration displacement given, simulation and analyses indicated that additional supports is more beneficial than heightening the rigidity of steel reinforced concrete in support pillars and adopting steel wrappers on the pillars to increase natural frequency of support structure. Increasing the rigidity of steel reinforced concrete, adopting steel wrappers and providing additional supports are all helpful in reducing three directions vibration Max displacement. and additional supports are comparatively more effective. Therefore, a structure scheme with steel reinforced concrete support pillars, steel wrappers and additional supports should be adopted in practical wind tunnel support construction.